如何使用 postgres 从子查询中获取行的关联数组

Question

我是 postgres 的新手，在从 mySQL 跳转之前尝试了一些东西。

我想做的是将关联数组的数组放入单个查询中。它与可以选择多种联系人类型（如电话、电子邮件和 Facebook）的用户有关，我想将这些类型检索到“联系人”列中。

对于可视化：

{
"first_name": "This",
"last_name": "is me",
"likes": [],
"city": null

}

我想得到这样的东西：

{
"first_name": "This",
"last_name": "Is me",
"likes": [],
"city": null,
"contact": 
    [
      {"type":1, "value":"myemail@gmail.com", "privacy_rule":1},
      {"type":4, "value":"myfacebook", "privacy_rule":1},
      {"type":9, "value":"mylinkedin", "privacy_rule":1}
    ]
}

所以主要查询是：

SELECT u.first_name, u.last_name, u.about, ARRAY(SELECT like_id FROM users_likes l WHERE l.user_id = u.user_id), u.city FROM users u WHERE user_id = {id}

子查询将是：

SELECT c.type, c.value, c.privacy_rule FROM users_contact c WHERE c.user_id = u.user_id

但是如何将它集成到主查询中以返回结果行数组呢？有可能吗？

提前致谢！

罗恩

Answer 1

啊，经过一番补充，这就是答案。使用 json_build_object：

SELECT u.first_name, u.last_name, 
ARRAY(SELECT like_id FROM users_likes l WHERE l.user_id = u.user_id) as likes, 
ARRAY(SELECT json_build_object("contact_id", c.contact_id, 
"value", c.value, "privacy",c.privacy) 
FROM users_contact c WHERE c.user_id = u.user_id) as contact 
FROM users_basic u WHERE user_id = {id}

这给出：

"first_name": "This",
"last_name": "Is Me",
"about": null,
"likes": [],
"city": null,
"contact": [
  {
    "contact_id": 1,
    "value": "bbla",
    "privacy": 2,
    "type": "Phone"
  },
  {
    "contact_id": 3,
    "value": "blabla",
    "privacy": 2,
    "type": "Company Email"
  },
  {
    "contact_id": 4,
    "value": "blablabla",
    "privacy": 2,
    "type": "Telegram Id"
  }
]

希望它可以帮助某人